[ironic][swift]Temporary add sha1 to allowed_digests

Swift removed sha1 from supported digests with [1] and
that broked ironic tinyipa job. Temorary add sha1 to
allowed_digests until it's fixed in ironic.

[1] https://review.opendev.org/c/openstack/swift/+/525771

Story: 2010068
Task: 45539
Change-Id: I68dfc472ce901058b6a7d691c98ed1641d431e54
1 file changed